and my problem is that i dont know how to make the brush fade at the end of each stroke like it is there, when i set it to fade in brushes window it only fades from left to right and it fades in the middle of the brush...what i have to do???

In the Brushes menu as seen in that hair demo. Click on the words "Other Dynamics" Then under the Flow Jitter option next to the work "Control" is a drop down menu. Select "pen pressure" from the drop down menu.

That worked for me, I use a very small wacom tablet. (well I barely use it, I mostly just use my mouse)

Oh ok, sorry I was under the impression that you were using a digital pen after reading Corto's post about the digital pen.

Ok, well I went into photoshop and looked at how to do it with a mouse. Basically just do the same thing, except select "Fade" from the drop down menu instead of "Pen Pressure". The only problem with this is that it will only allow the stroke to be a certain length. You'll have to adjust the number to the right of the drop down menu in increase or decrease the length of the stroke.

I just tested it out and it simmulates very well what's in that hair demo. Though like Corto said, Bobo is most likely using a digital pen with pressure sensitivity allowing him to control the fade and stroke length all at once.

You should be able to acheive the same results though with a mouse, it'll just be a bit slower and annoying as you'll have to manually change the lenght of the stroke as you go